There are various types of rotating equipment such as pumps and compressors which include a rotating shaft that is driven by a conventional motor. The equipment includes an equipment housing which surrounds the shaft and a passage which defines a bearing cavity or chamber through which the shaft extends. To rotatably support the shaft within the bearing cavity of the equipment housing, one or more conventional bearings are provided in the bearing cavity which bearings extend radially between an inward facing passage surface in the equipment housing and an outer shaft surface on the shaft and provide radial support to the shaft. This is a conventional arrangement.
The shaft itself may either be exiting the equipment housing or may be entering another equipment housing wherein the shaft is exposed to the outside environment as it enters or exits the housing.
Therefore, the housing has an opening which opens towards this exterior environment and has the passage surface which is spaced radially outwardly of the shaft surface. The bearing is located within the bearing cavity or chamber defined between such opposing surfaces. Typically, the bearing is spaced a desired axial distance from the outside end face of the housing. In the absence of any other sealing structure, atmospheric contamination such as dust, water, moisture, etc. can enter into the bearing cavity and enter into the bearings which can cause damage or decrease performance of the bearings.
To protect the bearings, mechanical devices known as bearing isolators or other equivalent terms have been developed which fit into the housing opening and span the distance between the housing surface and shaft surface. These bearing isolators include a rotor affixed to the shaft and a stator which is affixed to the equipment housing wherein the bearing isolator has closely spaced surfaces that define very narrow passages which prevent or impede the entry of any of such liquid, dust or other contaminates into the bearing space.
Generally, bearing isolators, also known as labyrinth seals are applied to a variety of rotating equipment having oil lubricated, greased, oil mist and unlubricated bearings wherein these bearing isolators serve to retain the lubricant in the bearings and/or prevent external contaminants from entering the bearing cavity. The opposed surfaces between the rotor and stator define a tortuous path to restrict the passage of fluids through the bearing isolator components. In some cases, a secondary static seal may also be provided in the bearing isolator to further restrict fluid when the seal is not in operation such as when the shaft is not rotating.
Conventional bearing isolators use a variety of shapes and features on the atmospheric side of the bearing isolator seal to prevent external contaminants from entering the bearing isolator. The most challenging contaminant to exclude is a high velocity water spray, which may come from an equipment wash down hose, pressure washer or in extreme weather events with high winds and rains. Various bearing isolator seal designs have been developed and these designs typically are developed to resist such contaminating conditions.
The object of the present invention is to provide an improved geometric configuration for the atmospheric side of a bearing isolator seal that provides more effective resistance to the ingress of contaminants, particularly, high velocity water spray.
In the improved arrangement of the present invention, a rotor and stator have projections which extend radially and axially. As to the stator, the stator mounts within the equipment housing and has a first radial projection against the housing to define an inboard set of geometric surfaces. The stator then extends axially and includes an outboard radial projection which is spaced axially from the inboard radial projection and extends radially, outwardly to a smaller extent than the inboard radial projection. These axially-spaced radial projections thereby define an annular groove bounded by groove side faces and a groove bottom face.
The rotor includes a radial projection which extends outwardly close to the outboard radial projection on the stator, and the rotor then includes an axial projection which turns in the inboard direction, towards the housing so as to lie closely adjacent to the terminal end of the radial projection on the stator. The radial outward facing surface on the stator radial projection and the opposing inward facing surface on the rotor axial projection define an entrance passageway which is necessary due to the relative rotation between the stator and rotor and these opposed surfaces thereof. The basic combination of a rotor and stator with these types of projections located close to each other is well known in the prior art.
The improved bearing isolator seal of the present invention includes an improved geometry which is believed to result in improved exclusion of contaminants in high velocity water spray from the bearing cavity of the rotating equipment. The bearing isolator seal employs several features as follows:
1) An annular groove on the stator which is defined between the inboard radial projection and the outboard radial projection wherein the stator groove has angled side surfaces on the inboard and outboard sides and no right angles wherein these angled side surfaces redirect incoming contaminants and high velocity spray and reduce the possibility of the incoming contaminant flow entering the restricted flow path defined by the entrance passageway referenced above.
2) An angled interface between the stator and rotor surfaces which define the entrance passageway and thereby increases the rotational effects of exclusion during shaft rotation. This angled feature of the entrance passageway also assists in the draining of contaminants from the bottom of the bearing isolator seal, even in a static condition while the shaft is not rotating.
3) The stator features the inboard radial projection which is larger than the outboard stator radial projection and any diameter on the rotor which further assists in redirecting spray and other contaminants.
Referencing the entrance passageway, the entrance passageway and the opposing surfaces between the rotor and stator are formed at an angle relative to the rotational axis of the equipment shaft. As such, the entrance passageway is at an angle of 5-45 degrees and preferably 15 degrees relative to the shaft axis. This passage angle enhances the centrifugal effects to eject any contaminants from the entrance of the passageway and also assist with draining at the bottom or 6 o'clock position of the seal when the equipment is not rotating. The entrance passageway communicates with the annular groove formed between the inboard and outboard radial projections on the stator.
The groove has the groove side faces which define the inboard and outboard faces thereof. The groove side faces each have an angular orientation or design wherein such groove surfaces are oriented at obtuse angles relative to the bottom groove surface. Each of the groove side faces is oriented at an angle of 95 to 135 degrees relative to the bottom groove surface and preferably is oriented at 105 degrees. Preferably, each groove side face is at the same angle in comparison to the other groove side face. These obtuse angles help to redirect an incoming high velocity spray out of the groove to minimize the amount of spray which can enter the entrance passageway. It is believed that traditional right angles reflect the same high velocity spray closer to the direction in which it comes and is more likely to enter the entrance passageway.
This arrangement is believed to provide improvements over other known bearing isolator seals.
Other objects and purposes of the invention, and variations thereof, will be apparent upon reading the following specification and inspecting the accompanying drawings.
Certain terminology will be used in the following description for convenience and reference only, and will not be limiting. For example, the words “upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer to directions in the drawings to which reference is made. The words “inwardly” and “outwardly” will refer to directions toward and away from, respectively, the geometric center of the arrangement and designated parts thereof. Said terminology will include the words specifically mentioned, derivatives thereof, and words of similar import.